Antidandruff shampoos are well known in the art and rely upon various actives for their antidandruff effectiveness. Such compositions are not only designed to relieve the dandruff condition, but also to effectively clean the hair.
U.S. Pat. No. 3,917,817, Vanlerberghe et al., issued Nov. 5, 1975, discloses a shampoo composition comprising a piperazine based cationic polymer active, 10% sodium alkyl sulfate, 4% lauryl monoethanolamide and 3% glycol distearate. U.S. Pat. No. 4,013,787, Vanlerberghe et al., issued Mar. 22, 1977, discloses similar compositions.
Pyridinethione slats are known for use as dandruff control actives. Specifically, 1-hydroxypyridinethione salts have been taught as antidandruff actives in lotion form shampoos. Included in this group is 2-zinc pyrithion (ZPT) as disclosed in U.S. Pat. No. 2,809,971, Bernstein, issued Oct. 15, 1957; U.S. Pat. No. 3,236,733, Karsten, issued Feb. 22, 1966; U.S. Pat. No. 3,753,916, Parran, issued Aug. 21, 1973; Japanese Published Application 60810, published May 19, 1977 (Lion Fat and Oil); U.S. Pat. No. 4,323,683, Bolich et al., issued Apr. 6, 1982; U.S. Pat. No. 4,345,080, Bolich, issued Aug. 17, 1982; U.S. Pat. No. 4,379,753, Bolich, issued Apr. 12, 1983; U.S. Pat. No. 4,470,982, Winkler, issued Sept. 11, 1984; and European Published Patent Application No. 285,388, published Oct. 5, 1988 abandoned.
In the present invention it has been surprisingly found that when a pyridinethione metal salt in platelet form, with a specified particle size, is combined with any of a group of specific synergizers in a shampoo matrix, an unexpected substantial improvement in antidandruff efficacy is realized. Such compositions are stable, safe and effective in cleaning the hair while treating the scalp for dandruff.